CGI::Fast

Section: Perl Programmers Reference Guide (3pm)
Updated: 2010-10-12
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NAME

CGI::Fast - CGI Interface for Fast CGI

SYNOPSIS

    use CGI::Fast qw(:standard);
    $COUNTER = 0;
    while (new CGI::Fast) {
        print header;
        print start_html("Fast CGI Rocks");
        print
            h1("Fast CGI Rocks"),
            "Invocation number ",b($COUNTER++),
            " PID ",b($$),".",
            hr;
        print end_html;
    }

DESCRIPTION

CGI::Fast is a subclass of the CGI object created by CGI.pm. It is specialized to work well FCGI module, which greatly speeds up CGI scripts by turning them into persistently running server processes. Scripts that perform time-consuming initialization processes, such as loading large modules or opening persistent database connections, will see large performance improvements.

OTHER PIECES OF THE PUZZLE

In order to use CGI::Fast you'll need the FCGI module. See http://www.cpan.org/ for details.

WRITING FASTCGI PERL SCRIPTS

FastCGI scripts are persistent: one or more copies of the script are started up when the server initializes, and stay around until the server exits or they die a natural death. After performing whatever one-time initialization it needs, the script enters a loop waiting for incoming connections, processing the request, and waiting some more.

A typical FastCGI script will look like this:

    #!/usr/bin/perl
    use CGI::Fast;
    &do_some_initialization();
    while ($q = new CGI::Fast) {
        &process_request($q);
    }

Each time there's a new request, CGI::Fast returns a CGI object to your loop. The rest of the time your script waits in the call to new(). When the server requests that your script be terminated, new() will return undef. You can of course exit earlier if you choose. A new version of the script will be respawned to take its place (this may be necessary in order to avoid Perl memory leaks in long-running scripts).

CGI.pm's default CGI object mode also works. Just modify the loop this way:

    while (new CGI::Fast) {
        &process_request;
    }

Calls to header(), start_form(), etc. will all operate on the current request.

INSTALLING FASTCGI SCRIPTS

See the FastCGI developer's kit documentation for full details. On the Apache server, the following line must be added to srm.conf:

    AddType application/x-httpd-fcgi .fcgi

FastCGI scripts must end in the extension .fcgi. For each script you install, you must add something like the following to srm.conf:

    FastCgiServer /usr/etc/httpd/fcgi-bin/file_upload.fcgi -processes 2

This instructs Apache to launch two copies of file_upload.fcgi at startup time.

USING FASTCGI SCRIPTS AS CGI SCRIPTS

Any script that works correctly as a FastCGI script will also work correctly when installed as a vanilla CGI script. However it will not see any performance benefit.

EXTERNAL FASTCGI SERVER INVOCATION

FastCGI supports a TCP/IP transport mechanism which allows FastCGI scripts to run external to the webserver, perhaps on a remote machine. To configure the webserver to connect to an external FastCGI server, you would add the following to your srm.conf:

    FastCgiExternalServer /usr/etc/httpd/fcgi-bin/file_upload.fcgi -host sputnik:8888

Two environment variables affect how the "CGI::Fast" object is created, allowing "CGI::Fast" to be used as an external FastCGI server. (See "FCGI" documentation for "FCGI::OpenSocket" for more information.)

FCGI_SOCKET_PATH: The address (TCP/IP) or path (UNIX Domain) of the socket the external FastCGI script to which bind an listen for incoming connections from the web server.
FCGI_LISTEN_QUEUE: Maximum length of the queue of pending connections.

For example:

    #!/usr/local/bin/perl    # must be a FastCGI version of perl!
    use CGI::Fast;
    &do_some_initialization();
    $ENV{FCGI_SOCKET_PATH} = "sputnik:8888";
    $ENV{FCGI_LISTEN_QUEUE} = 100;
    while ($q = new CGI::Fast) {
        &process_request($q);
    }

CAVEATS

I haven't tested this very much.

AUTHOR INFORMATION

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Address bug reports and comments to: lstein@cshl.org

BUGS

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